Ether of propylene glycol and process for making the same



V Patented Oct. 1, 1 929 UNITED STATES ETHER OI PROPYLENE GLYCOL AND PROCESS MAKING THE SAME No Drawing'.

I The invention relates to ethersof propylene glycol and processes for making such ethers.

' may be regarded as 5 glycol, C H (OH) The compounds comprised in the invention derived from by converting one or both of its hydroxyl groups to ether linkages and connecting thereto a corresponding number of alkyl or aryl groups. Examples of such compounds are:

monomethyl ether of propylene glycol (3,,H,OHOC,H monophenyl ether of propylene glycol 15 a s i dlethyl ether of propylene glycoL. Two general methods for preparing compounds of the above class will be described. When the desired product is a mono-ether,

propylene sodium dlethyl glycol hydroxld sulphate i propylene chlorhydrln the preferred'method of production is by th reaction of propylene oxid, C H O, with the appropriate alcohol, e. g.,

with propylene oxid at a temperature below the boiling point of the mixture. The mixture is sealed in an autoclave and heated to bring about the reaction. The reaction proceeds more rapidly as the temperature is mcreased, and the time required for the reaction to go to completion 1s correspondingly shortened. The increased temperature causes anincrease in pressure, the pressure being highest at first and subsequently dnmmshmg as Application filed July 20,

propylene by-products.

or nearly so, though detrimental effect other 1925. Serial No. 44,929.

the reacting materials are converted into the less volatile ether. Temperatures of 100 C. to 200 0., giving rise to maximum pressures of 100 to 500 pounds or more persquare inch are suitable, but either higher or lower temperatures may be used. The reaction may be completed in five hoursor less hlgh .temperature is used. p A considerable excess of the alcohol may if a sufficiently 1 j advantageously be employed to secure amore complete utilization of the propylene oxid, and to minimize the formation of undesired The ether is separated from" the unconsumed reagents and from-the by-products by fractional distillation.

Thedi-ethers may be prepared from propylene glycol or from propylene chlorhydrin. The following equations represent typical reactions by which di-ethers are formed:

dlethyl ether sodlum water of propylene In either of the reactions last described a portion of the propylene compound is converted to the mono-ether. The yield of diether is raised by increasing the quantity of diethylsulphate used beyond that required by the above equation. The alkali should be present in quantity at least suflicient to decompose completely the diethyl sulphate, and

to decompose the chlorhydrin, if used. Thereactingmaterials are preferably anhydrous the presence of water appears to have no than to decrease the yield.

The reaction mixture is boiled under a 'reflux condenser for three hours, more or less,

and the product is then distilled under reduced pressure. It may thereafter b'e redistilled, at normal or reducedv pressure, to effect its purification and a sufficient separation of the monoand di-ethers.

The ethers of propylene glycol are miscible with most of the common solvents, and either P PATENT orrlcs OF YONKEBS, NEW YORK, ASSIGNOR '10 CARBIDE AND CARBON A CORPORATION OF NEW YORK alone or in mixtures are valuable solvents for many diflicultly-soluble wsubstances, particu- .larly for gums, resins, and cellulose esters. When prepared for industrial use, it will often be unnecessary to prepare a single ether in pure form. A mixture of the monoand 5 di-ethers is highly useful as a solvent or reagent for many purposes. Mixtures of the et ers of propylene'glycol with ethers of the other lycols, such as the ethylene and butylene g ycols, are also useful for many purposes,- and when such mixtures can be used the purification of the materials from which the ether is to be formed may be avoided. Thus a mixture of olefins may be converted without separation into a mixture of chlorhydrins, glyco'ls, or olefin oxids, and these mixtures may be utilized in the processes described above for producing a mixture of ethers.

The boiling points of some of the monoethers of propylene glycol, at 7 36 mm. pressure, are as follows:

Deg. C.

Methyl. 122.8 13mm... 133.0 Isopropyl 141.5

Normal propyl 150.0 Isobutyl 161.3 Normal butyl 170.6 Isoamyl r 183.3

The structural ormulas of the propylene glycol ethers are not certainly known, but the mono-ethers are believed to be represented by the formula OH; time A HaOR. .o The (ii-ethers are distinguished from the, acetals of the same empirical formula by 4 having the ether linkages on diiferent carbon atoms.-

The alkyl ethers of propylene lycol have not been" prepared heretofore, so in as I am aware; I therefore claim as newsnbstances compounds having the type formula on o1vv where R is either a hydrogen atom or an 9 alkyl group, R is an'alkyl group, and OR and OR are attached to different carbon atoms.

I claim: 1. Propylene glycol ether represented by the formula B being an alkyl group orhydrogen, B being an alkyl group-and the OR and OR groups being attached to difierent carbon atoms.

2. Monomethyl ether of propylene glycol. In testimony whereof, I aflix my signature.

JOSEPH G. DAVIDSQN. 

